The invention is based on a fuel injection device for internal combustion engines as defined hereinafter. In a fuel injection device of this kind, known from German Patent 34 36 768, which serves to supply fuel to an internal combustion engine, a high pressure fuel pump, which is embodied as a piston pump, fills a pressure storage chamber with fuel via a high pressure line. Fuel injection lines lead from this pressure storage chamber to the individual fuel injection valves, which communicate with each other in common rail fashion; the pressure storage chamber is kept at a defined pressure by means of a pressure control device so that the injection pressure at the injection valves can be predetermined over the entire operational performance range of the engine to be supplied, independent of engine speed.
To control the injection times and quantities at the injection valve, an electrically actuated valve is inserted in each injection line, and with its opening and closing, controls the high pressure fuel delivery to the injection valve.
Upon opening of the electrical control valve, the fuel under high pressure flows into the injection valve, lifts a valve needle from its seat counter to the force of a valve spring, thus opening the injection valve, and the fuel is injected. The injection is brought to an end by means of the closing of the electrical control valve, which as a result causes the pressure in the injection valve to drop below the injection pressure, so that the restoring force of the valve spring brings the valve needle into contact with the valve seat.
The known fuel injection device has the disadvantage that the time of the injection onset and the time of the end of injection cannot be controlled precisely enough, since the time of the opening or closing motion of the electrical control valve is not identical to the start of the needle stroke of the injection valve, but deviates from it depending upon inertia as a result of the hydraulic connection between the two valves.
For modern internal combustion engines, however, in order to achieve an optimal mixture preparation and combustion, it is necessary to precisely adhere to the parameters of the injection time and duration, which cannot be reliably guaranteed with the known fuel injection device. Furthermore in the known invention, as a result of the inertia-encumbered triggering of the injection valve, with its necessarily very short switching times, it is not possible to sufficiently control a pre-injection quantity, which is of the utmost importance in connection with a reduction of the engine noise.